1. Field of the Invention
The present invention relates to a lens barrel to be mounted on an imaging apparatus such as a digital still camera or a digital video camera, and more particularly to a retractable lens barrel having a bending-type photographic optical system with a plurality of lens units.
2. Description of the Related Art
As a lens barrel to be mounted on an imaging apparatus such as a digital still camera or a digital video camera, there is conventionally known a lens barrel having a bending-type photographic optical system with a plurality of lens units (hereinafter, referred to as a “bending photographic optical system”). The bending photographic optical system does not require the arrangement of a plurality of lens units in line. Thus, an overall length required in an optical axis direction of an optical system can be shortened, and, therefore, the imaging apparatus can be thinned.
As an imaging apparatus that constitutes such a bending photographic optical system, for example, there is discussed an imaging apparatus where a light flux passing through a lens unit on an object side is bent 90 degrees by a prism and is then lead to another lens unit (see Japanese imaging apparatus, when viewed from an incident direction, the prism and a second lens unit disposed nearest to the object side of the prism are rotated in different directions in the inside of a tubular member holding the first lens unit to retract the first lens unit. In an imaging apparatus discussed in Japanese Patent Application Laid-Open No. 2009-169243, a reflecting member is brought into contact with any of a first lens unit frame, a second lens unit frame, a cam tube, and an intermediate tube, and then turned to retract lens units on an object side with respect to the reflecting member.
However, the technique discussed in Japanese Patent Application Laid-Open No. 2009-181102, the prism and the second lens unit are respectively rotated in different direction in the inside of the tubular member holding the first lens unit, when viewed from the incident optical axis direction. Thus, the outer diameter of the lens barrel including the tubular member holding the first lens unit may be increased.
In addition, the technique discussed in Japanese Patent Application Laid-Open No. 2009-169243, the reflecting member is disposed almost at the middle of the intermediate tube after being rotated. Thus, there is no degree of flexibility in placement of the lens unit or the lens unit frame on the object side with respect to the reflecting member at the time of retraction, and, therefore, the outer diameter of the lens barrel including the intermediate tube may be increased.